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Topic: Relativistic jet

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	7.1 Astrophysical jets
		At parsec scales the jets, observed via their synchrotron and inverse Compton emission at radio frequencies with VLBI imaging, appear to be highly collimated with a bright spot (the core) at one end of the jet and a series of components which separate from the core, sometimes at superluminal speeds.
		Finally, the morphology and dynamics of jets at kiloparsec scales are dominated by the interaction of the jet with the surrounding extragalactic medium, the jet power being responsible for dichotomic morphologies (the so called Fanaroff-Riley I and II classes [56], FR I and FR II, respectively).
		The dependence of the beam's internal structure on the flow speed suggests that relativistic effects may be relevant for the understanding of the difference between slower, knotty BL Lac jets and faster, smoother quasar jets [60].
	relativity.livingreviews.org /Articles/lrr-1999-3/node27.html (1247 words)

	Implications for jet physics
		In all models of jet launching from AGN by this mechanism, the jets emerge perpendicular to the axis of the disk.
		Figure 6 compares a model of the emission from a decelerating relativistic jet with VLA data for 3C31 at the same resolution.
		The (fitted) angle of the jet to the line of sight is 52°; the spine velocity decreases from 0.88c closest to the nucleus to 0.17c furthest from the nucleus, while the velocity at the edge of the jet decreases from 0.7c to 0.11c.
	www.cv.nrao.edu /~abridle/bgctalk/node6.html (1159 words)

	ScienceWeek
		A "relativistic jet" is a jet moving at close to the speed of light.
		Relativistic jets in some of these compact sources are found by means of multiwavelength observations with ground-based telescopes.
		From the observation of two-sided moving jets it is inferred that the ejecta in microquasars move with relativistic speeds similar to those believed to be present in quasars.
	scienceweek.com /2004/sb040227-5.htm (1880 words)

	Radio-loud and radio-quiet AGN
		Both the jets and halo are observed to be sources of continuum radio emission, presumably due to synchrotron emission from relativistic electrons in the jet/halo plasma.
		Although jets were originally hypothesised on the basis of theoretical arguments (Rees 1971), there are now many cases where modern radio imaging clearly reveals well-collimated jets linking the AGN with the halo.
		Relativistic bulk motion of the emitting jet plasma would result in significant aberration/beaming effects which could easily render the receding jet (known as the `counter-jet') almost undetectable in comparison with the approaching jet (known as the `jet').
	www.astro.umd.edu /~chris/publications/thesis/node4.html (476 words)

	Relativistic beaming - Wikipedia, the free encyclopedia
		Relativistic beaming is the process by which the relativistic effect modifies the apparent luminosity of a relativistic jet.
		When relativistic beaming occurs in such galaxies, a central supermassive fl hole is the ultimate source of energy for twin jets of intensely energetic plasma.
		Relativistic beaming is of particular importance for a jet which is oriented close to the line of sight from the AGN to Earth.
	en.wikipedia.org /wiki/Relativistic_beaming (1268 words)

	Introduction
		Jets and accretion disks are strongly related through a symbiosis, and we postulate that there may also be a large scale symbiosis involving dust components.
		The lack of emission lines and UV bump in blazars is usually assumed to be due to a low thermal activity at the centre, implying that the energy density of the external radiation is small in blazars compared to that in quasars.
		In Section 2 we shall discuss the optical/UV emission from an accretion disk in symbiosis with the jet, and its effect on the BLR emission clouds (ionized by disk photons) and the torus (heating of dust).
	www.physics.adelaide.edu.au /~adonea/paper1_html/node1.html (1095 words)

	CYGNUS X-3 AND THE COSMIC RAY QUESTION
		A one-side relativistic jet was observed in association with radio flare activity in Cygnus X-3 by Mioduszewski, et al (2001) using the VLBA in February 1997.
		Bipolar jets were also observed in October-November 2000 using the VLA and examined by the NRAO (Marti, et al, 2002), although whether or not these were a separate mechanism to the observed north-south orientated jets observed in 2001 has still to be decided.
		The 0.81c for the speed of Cygnus X-3s southern jet for the February 1997 observations (Mioduszewski et al, 2001) is based on estimates of jet motion in radio flaring, and does not necessarily relate to the initial velocity of ejecta on all frequencies.
	www.andrewcollins.com /page/articles/thecygnusmystery_cygnusx3.htm (4739 words)

	Galaxies and the Universe - Jets, Superluminal Motion, and Gamma-Ray Bursts
		The continuity of jets in direction indicates that the central generator has a memory over millions of years, and disk structures provide a natural way to control the direction of the jets.
		Many of the same considerations applicable to relativistic jets in AGN also seem to apply to gamma-ray bursts and their afterglows.
		In general, as a jet cools and becomes less relativistic, one expects a fading enhanced by a decline in the beaming factor, which would undergo a slope transition when the beaming factor is comparable to the jet's cone angle.
	www.astr.ua.edu /keel/galaxies/jets.html (2301 words)

	Relativistic Jet Model
		Thus, the mass flux in the jet is only about 1% of the mass flux into the BH, and more importantly, is only about 0.1% of the mass flux in the radiatively-driven wind, when the BH is attempting to accrete at a super-Eddington rate.
		This very low mass flux compared to the wind then implies that mixing between the jet and the thermal wind will be critical in determining whether the jet can escape (radio-loud) or is trapped within the radio photosphere of the wind determined by its free-free opacity at radio frequencies.
		Thus, for a given jet energy flux, this difference in the entrainment factor is in itself sufficient to explain the difference between the radio-quiet, and the radio-loud cases, respectively, provided that the entrainment has occurred below a radio photosphere.
	www.atnf.csiro.au /pasa/14_3/dopita/paper/node4.html (1040 words)

	Neutron Star Imitates Black Hole
		This is the first time such an ultra-relativistic jet has been seen from anything other than a super massive fl hole at the heart of a distant galaxy.
		Within the nebula lies the new-found jet of radio-emitting material thought to be associated with an accretion disk of material falling in towards the neutron star.
		Whatever process accelerates the jets to near the speed of light, it cannot therefore rely on the special properties of a fl hole.
	www.jb.man.ac.uk /news/CircinusX-1 (832 words)

	SHERPAS Team
		The JED is driving a mildly relativistic self-collimated electron-proton jet (MAES) which, when suitable conditions are met, is confining and inner ultra-relativistic electron-positron beam (the so-called two-flow model).
		However, such MHD jet are prone to be unstable with respect to purely MHD (current- and pressure-driven) instabilities, the outcome of which is still unknown on theoretical grounds.
		In this frame, the relativistic ejections could be associated with the explosive formation of dense pair plasma during so-called intermediate states, combining a still powerful jet and a luminous accretion disk.
	www-laog.obs.ujf-grenoble.fr /~petrucci/pageANR/SHERPASTeam.html (6849 words)

	X-ray binaries with relativistic jets -- microquasars
		All of these relativistic jets emit primarily via incoherent synchrotron emission from very high energy electrons spiralling in magnetic fields (although other emission mechanisms may contribute to the weak, flat spectral components which are sometimes observed).
		It may seem paradoxical that relativistic jets were first discovered in the nuclei of galaxies and distant quasars and that for more than a decade SS433 was the only known object of its class in our Galaxy (Margon 1984).
		At a probably distance of ~0.5 kpc, XTE J1819-254 is the closest relativistic jet source yet observed - with 1.5c and 0.6c for the apparent velocities for the approaching and receding jets.
	cats.sao.ru /~satr/XB (978 words)

	List Of Figures (Site not responding. Last check: 2007-09-11)
		Relativistic Glimm’s method is only used in regions with steep gradients.
		The density profile of the new states produced by the interaction of the two waves is shown in the bottom panel (note the change in scale on both axes with respect to the top panel).
		MPEG movie illustrating the propagation of a relativistic jet from a collapsar, whose progenitor is a rotating He star with a radius of
	www.univie.ac.at /EMIS/journals/LRG/Articles/lrr-2003-7/lof.html (1226 words)

	3C31 Relativistic Jet Animations
		The relativistic jet model used to generate these displays is the best fit to 8 GHz VLA data for 3C31 at 0.25 arcsec resolution by R.A.Laing and A.H.Bridle (2002: MNRAS, 336, 328).
		Throughout the flaring and outer regions, the velocity at the edge of the jet is approximately 0.7 of its on-axis value.
		The inferred transverse velocity profiles and field structure in the flaring region support the idea that the jets decelerate by entraining the external medium from the galactic atmosphere of 3C31.
	www.cv.nrao.edu /~abridle/3c31free/animations.htm (569 words)

	The Astrophysics Spectator: Gamma-ray Bursts
		The jet moves at nearly the speed of light, so that the kinetic energy of the material is hundreds or thousands of times greater than the rest mass of the material in the jet.
		The remainder of the energy is gradually lost as the jet interacts with its surroundings, causing the extended radio emission.
		The theory that is consistent with the radio observations is that a short-duration jet of material is moving at close to the speed of light and is spreading out into a narrow cone; the material is therefore a thin disk that has a diameter that increases proportionally with the distance from the jet source.
	www.astrophysicsspectator.com /topics/observation/GammaRayBursts.html (1059 words)

	Astromart News - Why do Jets Emanate from Quasars and Black Holes?
		The energy emitted from the jet in 3C273 probably comes from gas that falls toward a supermassive fl hole at the center of the quasar, but is redirected by strong electromagnetic fields into a collimated jet.
		At relativistic velocities (that is, when the particles are moving at close to the speed of light) these photons are emitted in a narrow cone.
		Since there would be insufficient time for the particles to shoot out from the fl hole at close to the speed of light and then release their energy as radiation as far out as they are seen, the particles have to be accelerated locally, where they produce their emission.
	www.astromart.com /news/news.asp?news_id=527 (931 words)

	Double helix in the quasar 3C273
		Observations of jets in AGN probe the behavior of extremely relativistic matter in the Universe, and provide a unique, remote ``laboratory'' for studying the most powerful cosmic phenomena such as supermassive fl holes and extragalactic accretion disks.
		The relativistic jet observed in the quasar 3C273 is one--sided, with no signs of emission on the counter--jet side at dynamic ranges of up to 16,000:1.
		Their model explains in detail the internal structure of the jet on scales of up to 30 milliarcseconds (~ 300 parsecs), accommodates the general morphology of the jet on scales of up to 100 milliarcseconds (~ 1 kiloparsec), and accounts for the observed periodic changes of the jet ejection angle.
	www.mpifr-bonn.mpg.de /staff/alobanov/3C273-Science (1105 words)

	Unveiling the secrets of the radio source 3C120
		Simulations of a relativistic jet emerging from the powerful radio galaxy 3C120 are currently being performed at the Max-Planck-Institut für Astrophysik by Miguel A. Aloy and Ewald Müller.
		In order to explain their enormous energy output extragalactic jets must be linked to very energetic astrophysical phenomena, like e.g., the ejection of relativistic plasma from the neighborhood of supermassive fl holes existing in the centers of active galaxies.
		If that is indeed the actual jet path, we will see only those parts of the helix where the jet is moving towards us, while all other parts of the jet cannot be observed.
	www.mpa-garching.mpg.de /HIGHLIGHT/2001/highlight0101_e.html (710 words)

	This Week in Astro Fluids » Recent astrophysical hydrodynamic and MHD research
		The deflection angle of the jet is influenced more by the density contrast of the cloud than by the beam Mach number of the jet.
		A relativistic jet with low relativistic beam Mach number can eventually be slightly bent after it crosses the dense cloud; however, we have not seen permanently bent structures in the interaction of a high relativistic beam Mach number jet with a cloud.
		The relativistic jet impacts on dense clouds do not necessarily destroy the clouds completely, and much of the cloud body can survive as a coherent blob.
	www.cita.utoronto.ca /~ljdursi/thisweek/pivot/entry.php?id=1050 (333 words)

	[54.03] Simulations of Relativistic Jet Formation (Site not responding. Last check: 2007-09-11)
		For some time, direct very long baseline interferometry imaging observations have shown that collimated, relativistic flow at speeds up to a Lorentz factor of 10 (0.995c) are possible in active galactic nuclei.
		Such jet flows already are difficult to achieve theoretically, and usually require the relativistic environment of a supermassive fl hole.
		While it is now generally accepted that jets, including relativistic ones, are accelerated and collimated by magnetized accretion disks, the Lorentz factors that have been achieved in these simulations still do not approach those suggested by IDVs or gamma-ray burst sources.
	www.aas.org /publications/baas/v31n5/aas195/87.htm (247 words)

	Jay's Gamma-ray Burst afterglow jet simulations
		The idea is that the gamma-ray burst event, lasting a few seconds, ejects a jet of matter at extreme relativistic velocity; very near the speed of light.
		Thus if we were to observe the Structured jet straight on, we would see a very energetic, short-lived afterglow, but if instead we observed the afterglow at a progressively higher angle of inclination from the jet axis, we would see a progressively less energetic, long-lived afterglow.
		This idea that observer perspective on a universal jet is the primary source of the variety of afterglows observed, coupled with the physical plausibility of nature making such a jet, with an energetic core and less energetic wings, makes this model quite appealing.
	home.comcast.net /~jdsalmonson/GRB_jets.html (1499 words)

	VLBI Images of Relativistic Galactic Jet Sources: SS433 and CI Cam (Site not responding. Last check: 2007-09-11)
		As in the classical extragalactic jets, individual components trace out a helical path as they move away from a compact core with speeds of order the speed of light.
		This data gives daily coverage of the evolution of the jet, allowing an examination of the dynamics and the flux variations of the individual components.
		CI Cam flared to 2 Crab in the X-ray on 1 April 1998; subsequent radio observations showed that this bright flare was associated with the appearance of a radio source at the position of CI Cam.
	www.aas.org /publications/baas/v30n2/aas192/abs/S074002.html (252 words)

	X-ray Binaries
		While remaing a unique and fascinating source, the radio jets from SS 433 have been rather overshadowed in the past five years by the discovery of highly relativistic jets from some bright fl-hole candidate (BHC) X-ray binaries.
		Jy-sensitivity is required to determine the population in the local group; angular resolution of 10 mas is desirable to resolve major ejections on a short timescale.
		High polarisation purity : a large amount of information regarding the composition and evolution of the relativistic ejecta may be inferred from observations of both linear and circular polarisation.
	www.ras.ucalgary.ca /SKA/science/node17.html (1132 words)

	IngentaConnect A transient relativistic radio jet from Cygnus X-1 (Site not responding. Last check: 2007-09-11)
		The jet was observed in only one of six epochs of MERLIN imaging of the source during a phase of repeated X-ray spectral transitions in 2004 Jan-Feb, and this epoch corresponded to the softest 1.5-12 keV X-ray spectrum.
		We discuss the resolved jet in terms of the recently proposed `unified model' for the disc-jet coupling in fl hole X-ray binaries, and tentatively identify the `jet line' for Cyg X-1.
		The source is consistent with the model in the sense that a steady jet appears to persist initially when the X-ray spectrum starts softening, and that once the spectral softening is complete the core radio emission is suppressed and transient ejecta/shock observed.
	www.ingentaconnect.com /content/bsc/mnr/2006/00000369/00000002/art00006 (395 words)

	Neutrino Astrophysics - Peter Meszaros
		Both the internal and the external reverse shocks are mildly relativistic, and are expected to lead to relativistic proton energy spectra of the form E^{-2}.
		Razzaque, Meszaros and Waxman (2005) investigated the possibility of semi-relativistic jets being present in core collapse supernovae which are not related to GRB, as suggested by anisotropic, polarized remnant observations.
		Razzaque and Meszaros (2006) considered a neutron-rich relativistic jet model of short bursts, which predicts a high energy neutrino and photon emission as neutrons and protons decouple.
	www.astro.psu.edu /users/nnp/nu.html (1814 words)

	Philip E. Hardee, Ph.D.
		Professor Hardee's research involves study of the highly collimated jet outflows observed to emanate from protostellar systems, from extragalactic radio sources and quasars, and thought to be responsible for gamma-ray bursts.
		Studies of relativistic jet dynamics have been carried out in collaboration with Dr. Philip Hughes at the University of Michigan in Ann Arbor.
		He is also involved in modeling extragalactic relativistic jet structures in collaboration with Dr. Craig Walker (NRAO/VLA), Dr. Jean Eilek (New Mexico Tech and NRAO) and Dr. Andrei Lobanov (Max Planck Institute).
	bama.ua.edu /~physics/faculty/hardee.html (433 words)

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